Get the bluetooth data from Blend Micro and save to a file


#1

Hello to everyone,

I have successfully managed to connect a sensor with a Blend Micro board and transmit the data through bluetooth to a smartphone, using the Simple Controls - Chat app and the BLE android examples here (https://github.com/RedBearLab/Android).

But I have zero experience in android developing and the one and only thing I want to change in the android app is to not just display the incoming data but to save them in a simple text file. Can someone help me and tell me which exactly is the variable in the example I should use to append to the text file?

Sorry for asking something that may seem to you very easy, but I tried, I have also read the guide here (https://developer.android.com/guide/topics/connectivity/bluetooth-le) but I just can’t get it.

Thank you in advance.


#2

Ok, I guess what I was looking for is inside the broadcastUpdate function and the EXTRA_DATA string.
But I want one thing more, to take the location and the time of the mobile client and insert it in the beginning of every incoming bluetooth message. Where should I put that? I have only managed to add something but it appears 4 times because (I guess) the message is big and divided to 4 blocks from blend micro. I want to show only one time before or after the bluetooth data that I receive on a regular basis.

Here is the code to not waste time searching:

package com.redbear.chat;

import java.util.UUID;

import android.app.Service;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothGatt;
import android.bluetooth.BluetoothGattCallback;
import android.bluetooth.BluetoothGattCharacteristic;
import android.bluetooth.BluetoothGattDescriptor;
import android.bluetooth.BluetoothGattService;
import android.bluetooth.BluetoothManager;
import android.bluetooth.BluetoothProfile;
import android.content.Context;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;
import android.util.Log;

/**
 * Service for managing connection and data communication with a GATT server
 * hosted on a given Bluetooth LE device.
 */
public class RBLService extends Service {
    private final static String TAG = RBLService.class.getSimpleName();
    private BluetoothManager mBluetoothManager;
    private BluetoothAdapter mBluetoothAdapter;
    private String mBluetoothDeviceAddress;
    private BluetoothGatt mBluetoothGatt;

    public final static String ACTION_GATT_CONNECTED = "ACTION_GATT_CONNECTED";
    public final static String ACTION_GATT_DISCONNECTED = "ACTION_GATT_DISCONNECTED";
    public final static String ACTION_GATT_SERVICES_DISCOVERED = "ACTION_GATT_SERVICES_DISCOVERED";
    public final static String ACTION_GATT_RSSI = "ACTION_GATT_RSSI";
    public final static String ACTION_DATA_AVAILABLE = "ACTION_DATA_AVAILABLE";
    public final static String EXTRA_DATA = "EXTRA_DATA";

    public final static UUID UUID_BLE_SHIELD_TX = UUID
            .fromString(RBLGattAttributes.BLE_SHIELD_TX);
    public final static UUID UUID_BLE_SHIELD_RX = UUID
            .fromString(RBLGattAttributes.BLE_SHIELD_RX);
    public final static UUID UUID_BLE_SHIELD_SERVICE = UUID
            .fromString(RBLGattAttributes.BLE_SHIELD_SERVICE);

    private final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {
        @Override
        public void onConnectionStateChange(BluetoothGatt gatt, int status,
                                            int newState) {
            String intentAction;

            if (newState == BluetoothProfile.STATE_CONNECTED) {
                intentAction = ACTION_GATT_CONNECTED;
                broadcastUpdate(intentAction);
                Log.i(TAG, "Connected to GATT server.");
                // Attempts to discover services after successful connection.
                Log.i(TAG, "Attempting to start service discovery:"
                        + mBluetoothGatt.discoverServices());
            } else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
                intentAction = ACTION_GATT_DISCONNECTED;
                Log.i(TAG, "Disconnected from GATT server.");
                broadcastUpdate(intentAction);
            }
        }

        public void onReadRemoteRssi(BluetoothGatt gatt, int rssi, int status) {
            if (status == BluetoothGatt.GATT_SUCCESS) {
                broadcastUpdate(ACTION_GATT_RSSI, rssi);
            } else {
                Log.w(TAG, "onReadRemoteRssi received: " + status);
            }
        }

        ;

        @Override
        public void onServicesDiscovered(BluetoothGatt gatt, int status) {
            if (status == BluetoothGatt.GATT_SUCCESS) {
                broadcastUpdate(ACTION_GATT_SERVICES_DISCOVERED);
            } else {
                Log.w(TAG, "onServicesDiscovered received: " + status);
            }
        }

        @Override
        public void onCharacteristicRead(BluetoothGatt gatt,
                                         BluetoothGattCharacteristic characteristic, int status) {
            if (status == BluetoothGatt.GATT_SUCCESS) {
                broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic);
            }
        }

        @Override
        public void onCharacteristicChanged(BluetoothGatt gatt,
                                            BluetoothGattCharacteristic characteristic) {
            broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic);
        }
    };

    private void broadcastUpdate(final String action) {
        final Intent intent = new Intent(action);
        sendBroadcast(intent);
    }

    private void broadcastUpdate(final String action, int rssi) {
        final Intent intent = new Intent(action);
        intent.putExtra(EXTRA_DATA, String.valueOf(rssi));
        sendBroadcast(intent);
    }

    private void broadcastUpdate(final String action,
                                 final BluetoothGattCharacteristic characteristic) {
        final Intent intent = new Intent(action);

        // This is special handling for the Heart Rate Measurement profile. Data
        // parsing is
        // carried out as per profile specifications:
        // http://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.heart_rate_measurement.xml
        if (UUID_BLE_SHIELD_RX.equals(characteristic.getUuid())) {
            final byte[] rx = characteristic.getValue();
            intent.putExtra(EXTRA_DATA, rx);
        }

        sendBroadcast(intent);
    }

    public class LocalBinder extends Binder {
        RBLService getService() {
            return RBLService.this;
        }
    }

    @Override
    public IBinder onBind(Intent intent) {
        return mBinder;
    }

    @Override
    public boolean onUnbind(Intent intent) {
        // After using a given device, you should make sure that
        // BluetoothGatt.close() is called
        // such that resources are cleaned up properly. In this particular
        // example, close() is
        // invoked when the UI is disconnected from the Service.
        close();
        return super.onUnbind(intent);
    }

    private final IBinder mBinder = new LocalBinder();

    /**
     * Initializes a reference to the local Bluetooth adapter.
     *
     * @return Return true if the initialization is successful.
     */
    public boolean initialize() {
        // For API level 18 and above, get a reference to BluetoothAdapter
        // through
        // BluetoothManager.
        if (mBluetoothManager == null) {
            mBluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
            if (mBluetoothManager == null) {
                Log.e(TAG, "Unable to initialize BluetoothManager.");
                return false;
            }
        }

        mBluetoothAdapter = mBluetoothManager.getAdapter();
        if (mBluetoothAdapter == null) {
            Log.e(TAG, "Unable to obtain a BluetoothAdapter.");
            return false;
        }

        return true;
    }

    /**
     * Connects to the GATT server hosted on the Bluetooth LE device.
     *
     * @param address The device address of the destination device.
     * @return Return true if the connection is initiated successfully. The
     * connection result is reported asynchronously through the
     * {@code BluetoothGattCallback#onConnectionStateChange(android.bluetooth.BluetoothGatt, int, int)}
     * callback.
     */
    public boolean connect(final String address) {
        if (mBluetoothAdapter == null || address == null) {
            Log.w(TAG,
                    "BluetoothAdapter not initialized or unspecified address.");
            return false;
        }

        // Previously connected device. Try to reconnect.
        if (mBluetoothDeviceAddress != null
                && address.equals(mBluetoothDeviceAddress)
                && mBluetoothGatt != null) {
            Log.d(TAG,
                    "Trying to use an existing mBluetoothGatt for connection.");
            if (mBluetoothGatt.connect()) {
                return true;
            } else {
                return false;
            }
        }

        final BluetoothDevice device = mBluetoothAdapter
                .getRemoteDevice(address);
        if (device == null) {
            Log.w(TAG, "Device not found.  Unable to connect.");
            return false;
        }
        // We want to directly connect to the device, so we are setting the
        // autoConnect
        // parameter to false.
        mBluetoothGatt = device.connectGatt(this, false, mGattCallback);
        Log.d(TAG, "Trying to create a new connection.");
        mBluetoothDeviceAddress = address;

        return true;
    }

    /**
     * Disconnects an existing connection or cancel a pending connection. The
     * disconnection result is reported asynchronously through the
     * {@code BluetoothGattCallback#onConnectionStateChange(android.bluetooth.BluetoothGatt, int, int)}
     * callback.
     */
    public void disconnect() {
        if (mBluetoothAdapter == null || mBluetoothGatt == null) {
            Log.w(TAG, "BluetoothAdapter not initialized");
            return;
        }
        mBluetoothGatt.disconnect();
    }

    /**
     * After using a given BLE device, the app must call this method to ensure
     * resources are released properly.
     */
    public void close() {
        if (mBluetoothGatt == null) {
            return;
        }
        mBluetoothGatt.close();
        mBluetoothGatt = null;
    }

    /**
     * Request a read on a given {@code BluetoothGattCharacteristic}. The read
     * result is reported asynchronously through the
     * {@code BluetoothGattCallback#onCharacteristicRead(android.bluetooth.BluetoothGatt, android.bluetooth.BluetoothGattCharacteristic, int)}
     * callback.
     *
     * @param characteristic The characteristic to read from.
     */
    public void readCharacteristic(BluetoothGattCharacteristic characteristic) {
        if (mBluetoothAdapter == null || mBluetoothGatt == null) {
            Log.w(TAG, "BluetoothAdapter not initialized");
            return;
        }

        mBluetoothGatt.readCharacteristic(characteristic);
    }

    public void readRssi() {
        if (mBluetoothAdapter == null || mBluetoothGatt == null) {
            Log.w(TAG, "BluetoothAdapter not initialized");
            return;
        }

        mBluetoothGatt.readRemoteRssi();
    }

    public void writeCharacteristic(BluetoothGattCharacteristic characteristic) {
        if (mBluetoothAdapter == null || mBluetoothGatt == null) {
            Log.w(TAG, "BluetoothAdapter not initialized");
            return;
        }

        mBluetoothGatt.writeCharacteristic(characteristic);
    }

    /**
     * Enables or disables notification on a give characteristic.
     *
     * @param characteristic Characteristic to act on.
     * @param enabled        If true, enable notification. False otherwise.
     */
    public void setCharacteristicNotification(
            BluetoothGattCharacteristic characteristic, boolean enabled) {
        if (mBluetoothAdapter == null || mBluetoothGatt == null) {
            Log.w(TAG, "BluetoothAdapter not initialized");
            return;
        }
        mBluetoothGatt.setCharacteristicNotification(characteristic, enabled);

        if (UUID_BLE_SHIELD_RX.equals(characteristic.getUuid())) {
            BluetoothGattDescriptor descriptor = characteristic
                    .getDescriptor(UUID
                            .fromString(RBLGattAttributes.CLIENT_CHARACTERISTIC_CONFIG));
            descriptor
                    .setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
            mBluetoothGatt.writeDescriptor(descriptor);
        }
    }

    /**
     * Retrieves a list of supported GATT services on the connected device. This
     * should be invoked only after {@code BluetoothGatt#discoverServices()}
     * completes successfully.
     *
     * @return A {@code List} of supported services.
     */
    public BluetoothGattService getSupportedGattService() {
        if (mBluetoothGatt == null)
            return null;

        return mBluetoothGatt.getService(UUID_BLE_SHIELD_SERVICE);
    }
}